"He was trying to get around getting caught, he was trying to keep it inside his email," detective David Nettles of the Houston Metro Internet Crimes Against Children Taskforce, told KHOU. "I can't see that information, I can't see that photo, but Google can."

Skillern is being held on a $200,000 bond, according to the report.

This case provides an illuminating example of Google's power to aid authorities in law enforcement. What once might have been private photographs are now being sent across servers monitored by Google.

And yet, it also fuels the controversy over Google's practice of scanning users' e-mails in order to target them with ads.

"Our automated systems analyze your content (including emails) to provide you personally relevant product features, such as customized search results, tailored advertising, and spam and malware detection," Google states in its Terms of Service. "This analysis occurs as the content is sent, received, and when it is stored." But as The BBC reported, those terms were updated after a class-action lawsuit was dismissed earlier this year over e-mail scanning.

Still, Google's role in policing compels the question among privacy advocates as to when it decides to take action on illicit content that crosses its servers.

In its Privacy Policy, Google lists a series of legal reasons that require it to share users' information with outside parties. Among those reasons, Google explains that it shares information in order to "protect against harm to the rights, property or safety of Google, our users or the public as required or permitted by law."

Last year, Google's director of giving, Jacquelline Fuller, wrote a blog post in which she outlined Google's commitment to stopping the spread of child pornography on the Web.

"We’re in the business of making information widely available, but there’s certain “information” that should never be created or found," she wrote. "We can do a lot to ensure it’s not available online—and that when people try to share this disgusting content they are caught and prosecuted."

However, there are forms of illegal activity that do not get scanned by Google in Gmail accounts, "such as pirated content or hate speech," according to The BBC.